Is this result trustable ?

[VL212]

My story (A) with a someone i date with (B) is:
- 13/4/2021: B had Unprotected Vaginal Sex (UVS) with husband
- 16/4/2021: A had UVS with someone.
- 23/4/2021: A had UVS with B
- 10/5/2021: A took Gen 4th Architect test, Negative.
- 13/5/2021: B took Gen 4th Architect test, Negative.
So do these results confirm that both were Negative till 23/4/2021 ? Should A take another test at 23/5/2021 to confirm his status ?

[Jim Allen]

So you had condomless intercourse twice.

The result you have is a good indicator, now to confirm your HIV status test with a blood-drawn HIV antibodies test at 6 weeks post-incident, a negative result at that time will rarely ever change. If you wish you can re-test at 3 months post-incident for peace of mind.

It would also be wise to get tested for far easier to acquire STI's.

B took Gen 4th Architect test, Negative.

So do these results confirm that both were Negative till 23/4/2021

Look the other person's test results are rather irrelevant. Just test when you are due.

Also, keep in mind that if you engage in condomless intercourse regardless if someone claims to have or has tested negative in the past you would still be accepting greater risk of acquiring HIV.

Here's what you need to know to avoid HIV infection:
Use condoms for anal or vaginal intercourse, correctly and consistently, every time, no exceptions. Consider talking to your health care provider about taking PrEP going forward as an additional layer of HIV protection.

Keep in mind that some sexual practices which may be described as ‘safe’ in terms of HIV transmission might still pose a risk for transmission of other STI's, so please do get fully tested regularly and at least yearly for all STI's including but not limited to HIV and test more frequently if unprotected intercourse occurs

Also, note that it is possible to have an STI and show no signs or symptoms and the only way of knowing is by testing.

Kind regards

Jim

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[VL212]

Thanks for your replies in advance.

I have 1 more question. Why are there countries and Dr suggest 28 days period as conclusive results for negative ? Is this period trustable to you ?

[Jim Allen]

Here is the short version. The median time to develop detectable antibodies is about 22- 28 days +-. A true four-week duo test provides high confidence with estimates in the 90-95% range, although some people take slightly longer.

The antibodies part of the test will screen against HIV 1 & 2 antibodies. The duo test also checks for p24 antigen in response to HIV 1 that is often present at detectable levels sooner but can drop off rapidly, by six weeks, a blood-drawn antibodies test or duo test you are looking at about 98%+ confidence.

We are conservative with the testing guidelines issued. Hence the recommendation to test at six weeks blood-drawn lab version, a negative result at that stage would rarely ever change. You can retest for a definite result for the rare/odd outlier at three months if you need that peace of mind.

If you are testing with rapid tests, they can be somewhat less sensitive to recent infections, and the rule of thumb is to wait and test at three months, and the result is considered conclusive.


2015
Taylor, D., Durigon, M., Davis, H., Archibald, C., Konrad, B., Coombs, D., et al. (2015). Probability of a false-negative HIV antibody test result during the window period: a tool for pre- and post-test counselling. Int. J. STD AIDS 26, 215–224. doi: 10.1177/0956462414542987

Patients typically want accurate test results as soon as possible while clinicians prefer to wait until the probability of a false-negative is virtually nil. This review summarizes the median window periods for third-generation antibody and fourth-generation HIV tests and provides the probability of a false-negative result for various days post-exposure. Data were extracted from published seroconversion panels. The median (interquartile range) window period for third-generation tests was 22 days (19-25) and 18 days (16-24) for fourth-generation tests. The probability of a false-negative result is 0.01 at 80 days' post-exposure for third-generation tests and at 42 days for fourth-generation tests.

Generation 3 & 4

http://i-base.info/guides/testing/test-accuracy-results-and-further-testing

http://i-base.info/guides/testing/appendix-1-different-types-of-hiv-test

Generation 4

2012
Rosenberg NE, Kamanga G, Phiri S, et al. Detection of acute HIV infection: a field evaluation of the determine(R) HIV-1/2 Ag/Ab combo test. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3318673/

Results. Of the participants 838 were HIV negative, 163 had established HIV infection, and 8 had acute HIV infection. For detecting acute HIV infection, the antigen portion had a sensitivity of 0.000 and a specificity of 0.983. For detecting established HIV infection, the antibody portion had a sensitivity of 0.994 and a specificity of 0.992.

2011
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222669/
Conclusions. Combo RT displayed excellent performance for detecting established HIV infection and poor performance for detecting acute HIV infection. In this setting, Combo RT is no more useful than current algorithms.

In total, 953 people underwent HIV testing. HIV antibody (Ab) prevalence was 1.8% (17/953). Four false positive rapid tests were identified: two antibody and two p24 antigen (Ag) reactions. Of participants diagnosed as HIV Ab positive, 2/17 (12%) were recent seroconverters based on clinical history and HIV antibody avidity test results. However, none of these were detected by the p24 antigen component of the rapid test kit. There were no other true positive p24 Ag tests.

https://www.cdc.gov/hiv/testing/clinical/index.html
2018
CDC recently published research findings that estimate the window period for 20 U.S. Food and Drug Administration (FDA)-approved HIV tests. The study showed that laboratory testing using antigen/antibody tests detects HIV infection sooner than other available tests that detect only antibodies. If a person gets a laboratory-based antigen/antibody test on blood plasma less than 45 days after a possible HIV exposure and the result is negative, follow-up testing can begin 45 days after the possible HIV exposure. For all other tests, CDC recommends testing again at least 90 days after exposure to be sure that a negative test result is accurate.

Bentsen C Performance evaluation of the Bio-Rad Laboratories GS HIV Combo Ag/Ab EIA, a 4th generation HIV assay for the simultaneous detection of HIV p24 antigen and antibodies to HIV-1 (groups M and O) and HIV-2 in human serum or plasma. Journal of Clinical Virology, S57-S61, 2011

Nick S Sensitivities of CE-Marked HIV, HCV, and HBsAg Assays. Journal of Medical Virology, S59-S64, 2007

Eshelman S Detection of Individuals With Acute HIV-1 Infection Using the ARCHITECT HIV Ag/Ab Combo Assay. Journal of Acquired Immune Deficiency Syndromes, 121-4, 2009

Speers D et al. Combination assay detecting both Human Immunodeficiency Virus (HIV) p24 antigen and anti-HIV antibodies opens a second diagnostic window. J Clin Microbiol 43:5397-5399, 2005

Ly TD et al. Evaluation of the sensitivity and specificity of six HIV combined p24 antigen and antibody assays. J Virol Methods 122:185-94, 2004

2020 http://www.bhiva.org/ https://www.bhiva.org/file/5dfceab350819/HIV-Testing-Guidelines.pdf
Recommendations (Grade 1A)

• Clinic policies and patient information regarding the HIV test window period should be based on 99th percentile estimates; where a test is undertaken sooner than this time interval, window period data should be used to counsel patients as to the likelihood of a false-negative result.

• Fourth-generation laboratory tests reliably exclude HIV by 45 days post-exposure, and this should be the window period applied when utilising these tests.

• Third-generation laboratory tests reliably exclude HIV by 2 months post-exposure, and this should be the window period applied when utilising these tests.

• POCTs reliably exclude HIV by 90 days post-exposure, and this should be the window period applied when utilising these tests.

2015 WHO http://apps.who.int/iris/bitstream/handle/10665/179870/9789241508926_eng.pdf;jsessionid=1F192FECF734A0DE7E2520864984AE63?sequence=1
In many settings post-test counselling messages recommend that all people who have a
non-reactive (HIV-negative) test result should return for retesting to rule out acute
infection that is too early for the test to detect. However, retesting is needed only for HIV-negative individuals who report recent or ongoing risk of exposure. For most people who test HIV-negative, additional retesting to rule out being in the window period is not necessary and may waste resources.

Generation 1/2/3

Pilcher CD et al. Performance of Rapid Point-of-Care and Laboratory Tests for Acute and Established HIV Infection in San Francisco. PLOS ONE, 2013.

Branson BM State of the art for diagnosis of HIV infection. Clin Infect Dis 45:S221-225, 2007

Coombs RW Clinical laboratory diagnosis of HIV-1 and use of viral RNA to monitor infection. In Holmes KK (editor), Sexually Transmitted Diseases. New York: McGraw-Hill, 2008

Maldarelli F Diagnosis of Human Immunodeficiency Virus infection. In Mandell, Douglas and Bennett’s Principles and Practice of Infectious Diseases (sixth edition). Philadelphia: Elsevier Churchill Livingstone, 2004

Parry JV et al. Towards error-free HIV diagnosis: guidelines on laboratory practice. Comm Dis Pub Health 6:334-350, 2003

3rd gen testing accuracy Perry KR et al. Improvement in the performance of HIV screening kits. Transfus Med 18:228-240, 2008